The first requirement of a thread clamp on a weaving machine is that it must be suitable for a wide range of threads. Textiles are always composed of several types of threads which have to be gripped in turn by the same thread clamp, for example the thread clamp of a feed gripper or receiving gripper or of a thread presentation mechanism.
A thread clamp should preferably be broad enough that it can handle a wide range of threads and yet not have to be reset or readjusted when changing from one type of textile to another.
Another important requirement is that the thread clamp should always operate with as much precision as possible, even when the mechanical parts become worn.
An important improvement which enables these requirements to be met is described in Belgian patent No. 902.141, corresponding to U.S. Pat. No. 4,708,174, made by the present applicant, concerning a thread clamp for weaving machine grippers which is characterised by a fixed bit which operates in conjunction with an elastically deformable wire spring, thus partly compensating for the effects of wear. Practical experience has since shown that this type of thread clamp is less suitable for certain types of thread, since thread fibres tend to come loose and to get wound round the wire spring, where they remain.